Hydraulic clutch and transmission device provided with the same

ABSTRACT

A hydraulic clutch including a clutch drum with an outer cylinder fitted with a plurality of clutch plates and a side wall; a clutch piston that defines together with the clutch drum an engagement oil chamber, and moves in an axial direction to press the clutch plates by hydraulic pressure supplied to the engagement oil chamber; and a cancel plate that defines together with the clutch piston a cancel oil chamber that cancels centrifugal hydraulic pressure. The side wall of the clutch drum is formed with a first oil passage that radially extends and is in communication with the engagement oil chamber, and a second oil passage that radially extends and is in communication with the cancel oil chamber. One of the first and second oil passages is at least partially included in a range of an axial width of the other of the first and second oil passages.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application Nos. 2011-074722 and2011-231179 filed on Mar. 30, 2011 and Oct. 20, 2011, respectively,including the specifications, drawings and abstracts are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a hydraulic clutch including a clutchdrum that is fitted with a plurality of clutch plates; a clutch pistonthat together with the clutch drum defines an engagement side oilchamber; and a cancel plate that together with the clutch piston definesa cancel oil chamber for canceling centrifugal hydraulic pressure, andalso relates to a transmission device provided with the hydraulicclutch.

DESCRIPTION OF THE RELATED ART

A past proposed example of a transmission device can transmit powerapplied to an input shaft to an output shaft, and change a speed ratioto a plurality of stages by switching the engagement states of aplurality of hydraulic clutches. The transmission device includes afirst clutch, and a second clutch that is disposed inward of the firstclutch so as to axially overlap with the first clutch (e.g., seeJapanese Patent Application Publication No. 2009-30654 (JP 2009-30654A)). The first clutch of this transmission device includes a clutch drumformed from an outer drum and an inner drum. The outer drum holds aplurality of friction plates. The inner drum can rotate together withthe outer drum, and holds a piston member that can move in the axialdirection so as to press the plurality of friction plates with a portionof the outer drum used as a cylinder. A first clearance that extendscircumferentially outward from the input shaft side of the transmissiondevice is provided between the outer drum and the inner drum as an oilpassage to a hydraulic servo of the first clutch. A second clearancethat extends circumferentially outward from the input shaft side of thetransmission device is provided between the clutch drum of the firstclutch and a clutch drum of the second clutch as an oil passage to acancel oil chamber of the first clutch.

SUMMARY OF THE INVENTION

However, in the transmission device according to the related artdescribed above, the radially-extending first clearance that serves asthe oil passage to the hydraulic servo and the radially-extending secondclearance that serves as the oil passage to the cancel oil chamber ofthe first clutch are arranged parallel in the axial direction. Thisincreases the axial length of the transmission device, and hindersefforts to make a hydraulic clutch and a transmission device providedwith the hydraulic clutch more compact. In addition, forming the firstclearance that serves as the oil passage to the hydraulic servo of thefirst clutch requires members other than the structural members of thefirst clutch (the clutch drum of the second clutch in the transmissiondevice of JP 2009-30654 A), which may increase the number of parts andresult in a more complicated and larger device overall.

The present invention provides a hydraulic clutch with a compact andsimple configuration, and a transmission device provided with thehydraulic clutch.

The hydraulic clutch of the present invention employs the following toachieve the above.

A hydraulic clutch according to the present invention includes a clutchdrum that includes at least an outer cylinder portion that is fittedwith a plurality of clutch plates, and a side wall portion; a clutchpiston that defines together with the clutch drum an engagement side oilchamber, and moves in an axial direction so as to press the clutchplates by hydraulic pressure supplied to the engagement side oilchamber; and a cancel plate that defines together with the clutch pistona cancel oil chamber that cancels centrifugal hydraulic pressure. In thehydraulic clutch, the side wall portion of the clutch drum is formedwith a first oil passage that radially extends and is in communicationwith the engagement side oil chamber, and a second oil passage thatradially extends and is in communication with the cancel oil chamber,and one of the first and second oil passages is at least partiallyincluded in a range of an axial width of the other of the first andsecond oil passages.

In the hydraulic clutch, the side wall portion of the clutch drum isformed with the first oil passage that radially extends and is incommunication with the engagement side oil chamber, and the second oilpassage that radially extends and is in communication with the canceloil chamber. In addition, one of the first and second oil passages is atleast partially included in the range of the axial width of the other ofthe first and second oil passages. Thus, the first oil passage forsupplying oil to the engagement side oil chamber and the second oilpassage for supplying oil to the cancel oil chamber are formed onsubstantially the same plane within the side wall portion of the clutchdrum. Therefore, the first and second oil passages are not formedparallel in the axial direction, and an increase in the axial length ofthe hydraulic clutch can be suppressed. In addition, the first andsecond oil passages are both formed within the side wall portion of theclutch drum. There is thus no need to use a separate member for formingthe oil passages. Moreover, an increase in the number of parts can besuppressed and the hydraulic clutch can have a more simple and downsizedconfiguration. Consequently, according to the present invention, ahydraulic clutch with a compact and simple configuration can beachieved.

The first oil passage and the second oil passage may each be formed in aplurality in the side wall portion of the clutch drum so as to alternatewith each other in a radiating manner. By thus forming the first andsecond oil passages so as to alternate with each other in a radiatingmanner, the first oil passages and the second oil passages do notoverlap with each other as viewed from the axial direction, and anincrease in the axial length of the hydraulic clutch can be suppressed.In addition, oil can be equally supplied to the engagement side oilchamber and the cancel oil chamber.

Further, the first and second oil passages may each be formed from ahole portion that is formed penetrating radially inward from an outerperiphery of the side wall portion of the clutch drum, and an openingportion of the hole portion positioned on an outer circumferential sideof the side wall portion may be closed by a lid element. Thus, the firstand second oil passages can be easily formed.

A transmission device according to the present invention is providedwith the hydraulic clutch according to any of the above descriptions,wherein the hydraulic clutch is a first hydraulic clutch. Thetransmission device further includes a second hydraulic clutch that isdisposed circumferentially inward of the first hydraulic clutch. Inother words, according to the present invention, an increase in theaxial length of the transmission device can be suppressed, while alsosupplying oil to the engagement side oil chamber and the cancel oilchamber of the first hydraulic clutch that is disposed outward of thesecond hydraulic clutch.

In addition, the second hydraulic clutch may include a second clutchdrum that is disposed circumferentially inward of the clutch drum; aclutch hub that is disposed circumferentially inward of the secondclutch drum; a plurality of second clutch plates that is fitted in analternating manner to an inner periphery of the second clutch drum andan outer periphery of the clutch hub; and a second clutch piston thatdefines together with the clutch drum a second engagement side oilchamber, and moves in the axial direction so as to press the secondclutch plates by hydraulic pressure supplied to the second engagementside oil chamber. A ring-shaped fixing portion may axially extend fromthe side wall portion of the clutch drum. An aligning portion may beformed axially extending from an inner circumferential side of thefixing portion, and the cancel plate of the first hydraulic clutch andthe second clutch drum may be fitted to the aligning portion of thefixing portion. The second oil passage may be in communication with thecancel oil chamber through an oil passage formed in the fixing portionof the clutch drum. It is thus possible to dispose the first hydraulicclutch and the second hydraulic clutch so as to overlap as viewed fromthe radial direction with the second oil passage and the cancel oilchamber in communication with each other.

The clutch drum may include an inner cylinder portion that axiallyextends from an inner circumferential portion of the side wall portion,and the inner cylinder portion may be fitted with a cylindrical sleevethat is rotatably supported by a fixed member of the transmission devicesuch that the sleeve rotates together with the inner cylinder portion.In addition, the first oil passage may be in communication with a firstsupply passage formed in the fixed member through a first oil holeformed in the sleeve and a first relay oil passage formed in the innercylinder portion, and the second oil passage may be in communicationwith a second supply passage formed in the fixed member through a secondoil hole formed in the sleeve and a second relay oil passage formed inthe inner cylinder portion. Thus, even if the first and second supplypassages formed in the fixed member of the transmission device have asimplified structure, the first and second oil passages can easily be inrespective communication with the first and second supply passages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view that shows an essential portion of anautomatic transmission 20 provided with clutches C1 and C2 according toan embodiment of the present invention;

FIG. 2 is a frontal view of a clutch drum 30 as seen from the right sidein FIG. 1;

FIG. 3 is an enlarged sectional view that shows a fixing portion 304 ofthe clutch drum 30 and a surrounding area;

FIG. 4 is an enlarged sectional view that shows a second oil passage 302c formed in a first side wall portion 302 of the clutch drum 30 and asurrounding area;

FIG. 5 is an enlarged sectional view that shows a portion of contactbetween a sleeve 52 and a stepped portion 303 d of an inner cylinderportion 303 of the clutch drum 30;

FIG. 6 is an enlarged view of an essential portion that shows an endportion of the sleeve 52; and

FIG. 7 is an enlarged sectional view that shows the fixing portion 304of the clutch drum 30 and the surrounding area.

DETAILED DESCRIPTION OF THE EMBODIMENT

Next, an embodiment of the present invention will be described.

FIG. 1 is an enlarged sectional view that shows an essential portion ofan automatic transmission 20 provided with clutches C1 and C2 accordingto an embodiment of the present invention. The automatic transmission 20according to the embodiment is configured as a stepped transmission andmounted in a vehicle. As shown in FIG. 1, the automatic transmission 20includes an input shaft 21, as well as the clutches C1 and C2, aplurality of other clutches and brakes (not shown), and a planetary gearmechanism 50 for changing a power transmission path from the input shaft21 to an output shaft (not shown). The clutches C1 and C2, the pluralityof other clutches and brakes, and the planetary gear mechanism 50 areaccommodated inside a transmission case (not shown). Note that the inputshaft 21 of the automatic transmission 20 is connected to a crankshaftof an engine through a torque converter or the like, and the outputshaft is connected to a drive wheel through a differential mechanism(differential gear) or the like (none of which are shown in thedrawings).

The clutch C1 is configured as a multi-plate friction hydraulic clutch.The clutch C1 includes a clutch drum 30 that is supported rotatablearound the input shaft 21 through a bearing 51; a clutch hub 31 that isfixed to a ring gear, for example, of the planetary gear mechanism 50; aplurality of ring-shaped clutch plates (mating plates) 32 that isslidably supported on an inner circumferential surface of the clutchdrum 30 through a spline; a plurality of ring-shaped clutch plates(friction plates) 33 that is slidably supported on an outercircumferential surface of the clutch hub 31 through a spline; a clutchpiston 35 that is fitted axially slidable on the inner circumferentialsurface of the clutch drum 30 and movable toward the clutch plates 32,33, and defines together with the clutch drum 30 a first engagement sideoil chamber 34; a cancel plate 36 that defines together with the clutchpiston 35 a first cancel oil chamber 37 for canceling centrifugalhydraulic pressure generated inside the first engagement side oilchamber 34; and a return spring 38 that is disposed between the clutchpiston 35 and the cancel plate 36. The clutch drum 30 is configured froma first outer cylinder portion 301 that is fitted with the clutch plates32, a first side wall portion 302 that extends radially inward from anend of the first outer cylinder portion 301, and an inner cylinderportion 303 that axially extends from an inner circumferential portionof the first side wall portion 302. The inner cylinder portion 303 ofthe clutch drum 30 is press-fit (fitted) with a sleeve 52 so as toenable the sleeve 52 to rotate together with the inner cylinder portion303. The sleeve 52 is rotatably supported by a fixed member (fixedshaft) 600 that is integrated with the transmission case, for example,and rotatably supports the input shaft 21. Thus, the clutch drum 30 isrotatable around the axis of the input shaft 21. One end surface (on theleft side of the figure) of the sleeve 52 contacts an inner surface of astepped portion 303 d formed on the inner cylinder portion 303, wherebythe sleeve 52 is positioned in the axial direction.

The clutch C2 is configured as a multi-plate friction hydraulic clutch,and disposed circumferentially inward of the clutch C1 so as to overlapwith the clutch C1 as viewed from the radial direction. The clutch C2includes a clutch drum (second clutch drum) 40 that contacts (axiallysupports) a radially-extending inner circumferential portion of thecancel plate 36 biased by the return spring 38 toward the left side ofthe figure, and fastened to the clutch drum 30 together with the cancelplate 36; a clutch hub 41 that is fixed to a carrier, for example, ofthe planetary gear mechanism 50; a plurality of ring-shaped clutchplates (mating plates) 42 that is slidably supported on an innercircumferential surface of the clutch drum 40 through a spline; aplurality of ring-shaped clutch plates (friction plates) 43 that isslidably supported on an outer circumferential surface of the clutch hub41 through a spline; a clutch piston 45 that is fitted axially slidableon the inner circumferential surface of the clutch drum 40 and movabletoward the clutch plates 42, 43, and defines together with the clutchdrum 30 a second engagement side oil chamber 44; a cancel plate 46 thatdefines together with the clutch piston 45 a second cancel oil chamber47 for canceling centrifugal hydraulic pressure generated inside thesecond engagement side oil chamber 44; and a return spring 48 that isdisposed between the clutch piston 45 and the cancel plate 46. Theclutch drum 40 is configured from a second outer cylinder portion 401that supports the clutch plates 42, and a second side wall portion 402that extends radially inward from an end of the second outer cylinderportion 401.

A ring-shaped fixing portion 304 extends axially inward from asubstantially radial center portion of the first side wall portion 302of the clutch drum 30 of the clutch C1. A ring-shaped aligning portion305 also extends axially inward from an end portion on the innercircumferential side of the fixing portion 304. The cancel plate 36 ofthe clutch C1 includes an outer circumferential portion 361 thatslidingly contacts an inner circumferential portion of the clutch piston35 through a seal member; a coupling portion 362 that axially extendsfrom the outer circumferential portion 361; and an inner circumferentialportion 363 that extends radially inward from the coupling portion 362.One end surface of the inner circumferential portion 363 contacts aradially inward end surface of the fixing portion 304 of the clutch drum30 and the other end surface of the inner circumferential portion 363contacts the second side wall portion 402 of the clutch drum 40 of theclutch C2. In this state, the cancel plate 36 is fitted to an outercircumferential surface of the aligning portion 305, which extends fromthe fixing portion 304, together with the second side wall portion 402of the clutch drum 40.

FIG. 2 is a frontal view of the clutch drum 30 as seen from the rightside in FIG. 1. FIG. 3 is an enlarged sectional view that shows anessential portion of the fixing portion 304. As shown in the figures,the fixing portion 304 of the clutch drum 30 is formed with a pluralityof rivet holes 306 that extends axially inward from an end surface ofthe first side wall portion 302 of the clutch drum 30. Each of theplurality of rivet holes 306 is formed of a first hole portion 306 athat extends axially inward from the end surface of the first side wallportion 302, a second hole portion 306 b that extends axially inwardfrom the first hole portion 306 a such that an inner diameter of thesecond hole portion 306 b gradually decreases, and a third hole portion306 c that extends further axially inward from the second hole portion306 b such that an inner diameter of the third hole portion 306 cgradually decreases. The cancel plate 36 of the clutch C1 is also formedwith a plurality of rivet holes 363 a, each of which is in communicationwith the third hole portion 306 c of the rivet hole 306 of the fixingportion 304 when the inner circumferential portion 363 of the cancelplate 36 is fitted to the aligning portion 305. In addition, the secondside wall portion 402 of the clutch drum 40 of the clutch C2 is formedwith a plurality of rivet holes 402 a, each of which is in communicationwith the rivet hole 363 a of the cancel plate 36 when the innercircumferential portion of the second side wall portion 402 is fitted tothe aligning portion 305. A rivet 53 is inserted in the rivet holes 306,363 a, and 402 a. The rivet 53 is caulked from axially outward of theclutch drum 30 to fasten together the cancel plate 36 and the secondside wall portion 402 of the clutch drum 40 to the fixing portion 304 ofthe clutch drum 30. Thus, the clutch drum 30, the cancel plate 36, andthe clutch drum 40 can be easily fastened together, and the cancel plate36 is axially supported by the second side wall portion 402 of theclutch drum 40 that contacts the inner circumferential portion 363. Notethat the clutch drum 30, the cancel plate 36, and the clutch drum 40 maybe fastened together by a bolt and a nut.

The clutch piston 35 of the clutch C1 is supported axially slidable bythe fixing portion 304 of the clutch drum 30 through a seal member, andslidingly contacts an inner circumferential surface of the first outercylindrical portion 301 of the clutch drum 30 through a seal member. Theclutch piston 35 thus defines, together with the first outer cylinderportion 301, the first side wall portion 302, and the fixing portion 304of the clutch drum 30, the first engagement side oil chamber 34. Theclutch piston 45 of the clutch C2 is supported axially slidable by theinner cylinder portion 303 of the clutch drum 30 through a seal member,and slidingly contacts an inner circumferential surface of the fixingportion 304 of the clutch drum 30 through a seal member. The clutchpiston 45 thus defines, together with the inner cylinder portion 303,the first side wall portion 302, and the fixing portion 304 of theclutch drum 30, the second engagement side oil chamber 44. By utilizingthe fixing portion 304 formed on the first side wall portion 302 of theclutch drum 30 in this manner, the clutches C1 and C2 can be easilyconfigured.

The fixed member 600 is foamed with supply passages 31 a, 31 b that areconnected to a hydraulic control device (not shown) through an oilpassage (not shown) formed in the input shaft 21. The fixed member 600is also formed with a supply passage 31 c to which drained hydraulic oilis supplied from a hydraulic circuit of a lubrication system (not shown)that supplies lubricating oil to a lubrication target such as theplanetary gear mechanism 50 mounted in the automatic transmission 20. Inaddition, the sleeve 52 press-fit to the clutch drum 30 of the clutch C1is formed with an oil hole 52 a that is in communication with the supplypassage 31 a formed in the fixed member 600, and an oil hole 52 b thatis in communication with the supply passage 31 b. The inner cylinderportion 303 of the clutch drum 30 is formed with a relay oil passage 303a that is in communication with the oil hole 52 a of the sleeve 52, anda relay oil passage 303 b that is in communication with the oil hole 52b. The relay oil passage 303 b is in communication with the secondengagement side oil chamber 44. As shown in FIGS. 1 and 2, the firstside wall portion 302 of the clutch drum 30 is formed with a plurality(four in the embodiment) of first oil passages 302 a that radiallyextend in a radiating manner. Each of the plurality of first oilpassages 302 a on the inner circumferential side thereof is incommunication with the relay oil passage 303 a formed in the innercylinder portion 303, and also in communication with the firstengagement side oil chamber 34 through an oil passage 302 b that is morecircumferentially outward than the fixing portion 304 and axiallyextends through an inner portion of the first side wall portion 302.Thus, the hydraulic control device and the first engagement side oilchamber 34 are connected through the supply passage 31 a of the fixedmember 600, the relay oil passage 303 a of the inner cylinder portion303 of the clutch drum 30, and the first oil passage 302 a and the oilpassage 302 b of the first side wall portion 302. Also, the hydrauliccontrol device and the second engagement side oil chamber 44 areconnected through the supply passage 31 b of the fixed member 600, andthe relay oil passage 303 b of the inner cylinder portion 303 of clutchdrum 30.

In addition, the sleeve 52 press-fit to the clutch drum 30 of the clutchC1 is formed with an oil hole 52 c that is in communication with asupply passage 31 c formed in the fixed member 600. The inner cylinderportion 303 of the clutch drum 30 is formed with a relay oil passage 303c that is in communication with the oil hole 52 c of the sleeve 52. Therelay oil passage 303 c is formed so as to axially extend on an innercircumferential surface of the inner cylinder portion 303 of the clutchdrum 30, and an end (an end portion on the left side of FIG. 1) of therelay oil passage 303 c radially extends and is in communication withthe second cancel oil chamber 47 of the clutch C2. As shown in FIGS. 1and 2, the first side wall portion 302 of the clutch drum 30 is formedwith a plurality (four in the embodiment) of second oil passages 302 cthat radially extend in a radiating manner that alternates with theplurality of first oil passages 302 a so as not to overlap with theplurality of first oil passages 302 a as viewed from the axialdirection. Each of the plurality of second oil passages 302 c on theinner circumferential side thereof is in communication with the relayoil passage 303 c formed in the inner cylinder portion 303, and also incommunication with the first cancel oil chamber 37 through an oilpassage 302 d that axially extends through an inner portion of thefixing portion 304. Thus, a draining oil passage of the hydrauliccircuit of the lubrication system and the first cancel oil chamber 37communicate through the supply passage 31 c of the fixed member 600, therelay oil passage 303 c of the inner cylinder portion 303 of the clutchdrum 30, the second oil passage 302 c of the first side wall portion302, and the oil passage 302 d. Also, the draining oil passage of thehydraulic circuit of the lubrication system and the second cancel oilchamber 47 communicate through the supply passage 31 c of the fixedmember 600, and the relay oil passage 303 c of the inner cylinderportion 303 of clutch drum 30. In the embodiment, as shown in FIG. 1, anaxial width Da of the first oil passage 302 a and an axial width Dc ofthe second oil passage 302 c are set uniform. In other words, the secondoil passage 302 c is included within the range of the axial width Da ofthe first oil passage 302 a, and the first oil passage 302 a is includedwithin the range of the axial width Dc of the second oil passage 302 c.By thus forming the first oil passages 302 a and the second oil passages302 c on substantially the same plane inside the first side wall portion302, an increase in the axial length of the clutches C1, C2 can besuppressed. In addition, by alternately forming the first oil passages302 a and the second oil passages 302 c as viewed from the axialdirection, the first oil passages 302 a and the second oil passages 302c do not overlap with each other as viewed from the axial direction, andan increase in the axial length of the clutch C1 as well as that of theautomatic transmission 20 that includes the clutch C1 and the clutch C2can be suppressed. In addition, hydraulic oil can be equally supplied tothe first engagement side oil chamber 34 and the first cancel oilchamber 37 formed into ring shapes. Here, as shown by an arrow in FIG.4, the first and second oil passages 302 a, 302 c described above can beeasily formed by forming a hole portion penetrating radially inward froman outer periphery of the first side wall portion 302 of the clutch drum30, and then press-fitting a plug (lid element) 54 to an opening portionof the hole portion positioned on the outer circumferential side of thefirst side wall portion 302 as shown by a white arrow in FIG. 4 to closethe opening portion.

FIG. 5 is an enlarged sectional view that shows a portion of contactbetween the sleeve 52 and the stepped portion 303 d of the innercylinder portion 303 of the clutch drum 30. FIG. 6 is an enlarged viewof an essential portion that shows an end portion of the sleeve 52. Asshown in the figures, at the end portion of the sleeve 52, a firstpassage 521 is formed at a plurality of locations (eight locations inthe embodiment) on an outer periphery of the sleeve 52. Each firstpassage 521 is in communication with the relay oil passage 303 c formedin the inner circumferential surface of the inner cylinder portion 303of the clutch drum 30, and axially extends toward an end surface 520that contacts the stepped portion 303 d of the inner cylinder portion303. In addition, at the end portion of the sleeve 52, a second passage522 is formed at a plurality of locations (eight locations in theembodiment). Each second passage 522 is formed more axially recessedthan the end surface 520 that contacts the stepped portion 303 d of theinner cylinder portion 303, and radially extending to providecommunication between the first passage 521 and an inner portion of thesleeve 52. The second passage 522 is formed so as to open widest at aposition that is in communication with the first passage 521, andgradually narrow in the axial direction in the vicinity of a radialcenter portion of the sleeve 52 from the position at which the secondpassage 522 is in communication with the first passage 521, after whichthe second passage 522 has the same cross-sectional shape up to theinner circumferential surface of the sleeve 52. The stepped portion 303d of the inner cylinder portion 303 is formed with an oil passage 303 eas shown in the figure.

Next, the operation to supply hydraulic oil to the oil chambers of theclutches C1, C2 of the automatic transmission 20 thus configured will bedescribed. When engaging the clutch C1 of the embodiment, hydraulic oilfrom the hydraulic control device is supplied to the first engagementside oil chamber 34 through the supply passage 31 a of the fixed member600, the relay oil passage 303 a of the inner cylinder portion 303 ofthe clutch drum 30, and the first oil passage 302 a and the oil passage302 b of the first side wall portion 302. Thus, hydraulic pressureacting on the first engagement side oil chamber 34 causes the clutchpiston 35 to move toward the clutch plates 32, 33 such that the clutchplates 32, 33 are sandwiched between the clutch piston 35 and a contactmember fixed to the clutch drum 30, thus coupling the clutch drum 30 andthe clutch hub 31 by the friction force acting between the clutch plates32, 33. When disengaging the clutch C1, the hydraulic control device(not shown) stops the supply of hydraulic pressure to the firstengagement side oil chamber 34, and the clutch piston 35 is biased bythe return spring 38 to move toward the reverse side of the clutchplates 32, 33, thus disengaging the coupling of the clutch drum 30 andthe clutch hub 31. When engaging the clutch C2, hydraulic oil from thehydraulic control device is supplied to the second engagement side oilchamber 44 through the supply passage 31 b of the fixed member 600, andthe relay oil passage 303 b of the inner cylinder portion 303 of theclutch drum 30. Thus, hydraulic pressure acting on the second engagementside oil chamber 44 causes the clutch piston 45 to move toward theclutch plates 42, 43 such that the clutch plates 42, 43 are sandwichedbetween the clutch piston 45 and a contact member fixed to the clutchdrum 40, thus coupling the clutch drum 40 and the clutch hub 41 by thefriction force acting between the clutch plates 42, 43. When disengagingthe clutch C2, the hydraulic control device (not shown) stops the supplyof hydraulic pressure to the second engagement side oil chamber 44, andthe clutch piston 45 is biased by the return spring 48 to move towardthe reverse side of the clutch plates 42, 43, thus disengaging thecoupling of the clutch drum 40 and the clutch hub 41.

If the automatic transmission 20 is operated with the first and secondengagement side oil chambers 34, 44 filled with hydraulic oil asdescribed above, centrifugal hydraulic pressure is generated in thefirst and second engagement side oil chambers 34, 44. Therefore, even ifthe supply of hydraulic pressure to the first and second engagement sideoil chambers 34, 44 is stopped in order to disengage the clutches C1 andC2, the clutch pistons 35, 45 may remain pressed axially inward (towardthe left side in FIG. 1) by the centrifugal hydraulic pressure, thusdelaying disengagement of the clutches C1, C2. Therefore, when theautomatic transmission 20 operates with the first and second engagementside oil chambers 34, 44 filled with hydraulic oil, the drainedhydraulic oil from the hydraulic circuit of the lubrication system issupplied to the first cancel oil chamber 37 of the clutch C1 through thesupply passage 31 c of the fixed member 600, the relay oil passage 303 cof the inner cylinder portion 303 of the clutch drum 30, and the secondoil passage 302 c of the first side wall portion 302, and the oilpassage 302 d. Also, the drained hydraulic oil from the hydrauliccircuit of the lubrication system is supplied to the second cancel oilchamber 47 of the clutch C2 through the supply passage 31 c of the fixedmember 600, and the relay oil passage 303 c of the inner cylinderportion 303 of clutch drum 30. As a consequence, centrifugal hydraulicpressure is also generated in the first and second cancel oil chambers37, 47, and the centrifugal hydraulic pressure presses the clutchpistons 35, 45 axially outward (toward the right side in FIG. 1) so thata force caused by the centrifugal hydraulic pressure generated in thefirst and second engagement side oil chambers 34, 44 and acting on theclutch pistons 35, 45 can be canceled out.

In this case, immediately after the vehicle starts operating, the firstand second cancel oil chambers 37, 47 are not fully filled withhydraulic oil and there is still air inside the first and second canceloil chambers 37, 47. The air still inside the first cancel oil chamber37 is discharged to outside the clutch C1 through the oil passage 302 d,the second oil passage 302 c of the first side wall portion 302, therelay oil passage 303 c of the inner cylinder portion 303 of the clutchdrum 30, and the first and second passages 521, 522 formed in the sleeve52 when hydraulic oil is supplied to inside the first cancel oil chamber37. The air still inside the second cancel oil chamber 47 is dischargedto outside the clutch C2 through the oil passage 302 d, the second oilpassage 302 c of the first side wall portion 302, the relay oil passage303 c of the inner cylinder portion 303 of the clutch drum 30, and thefirst and second passages 521, 522 formed in the sleeve 52. At suchtime, hydraulic oil having a high specific gravity moves by centrifugalforce circumferentially outward inside the first and second cancel oilchambers 37, 47, which causes air inside the first and second cancel oilchambers 37, 47 to move circumferentially inward. Therefore, by usingthe second passage 522 that extends radially inward along the endsurface 520 of the sleeve 52 as part of a path for discharging air, theair inside the first and second cancel oil chambers 37, 47 can bequickly discharged to outside while also suppressing an outflow ofhydraulic oil through the second passage 522. In addition, the secondpassage 522 that provides communication between the first passage 521and the inner portion of the sleeve 52 extends from the outercircumferential surface to the inner circumferential surface of thesleeve 52. Therefore, the zero-origin of the centrifugal hydraulicpressure in the first and second cancel oil chambers 37, 47 cancorrespond to the inner circumferential surface of the sleeve 52. As aconsequence, it is possible to suppress the outflow of hydraulic oilwhile promoting the discharge of air when filling the first and secondcancel oil chambers 37, 47 with hydraulic oil, and more suitably securecentrifugal hydraulic pressure in the first and second cancel oilchambers 37, 47. Note that the air discharged to outside the clutchesC1, C2 through the first and second passages 521, 522 of the sleeve 52is discharged through an inner portion of the transmission case tooutside the vehicle. Once the hydraulic oil inside the first and secondcancel oil chambers 37, 47 is discharged through the first and secondpassages 521, 522 of the sleeve 52, the hydraulic oil flows back to anoil pan (not shown) after being supplied to the lubrication target,i.e., the planetary gear mechanism 50, through the oil passage 303 eformed in the stepped portion 303 d of the inner cylinder portion 303 ofthe clutch drum 30, and a gap of the bearing 51.

Thus, when the automatic transmission 20 is operated with the firstcancel oil chamber 37 filled with hydraulic oil and centrifugalhydraulic pressure is generated in the first cancel oil chamber 37, thecentrifugal hydraulic pressure causes the inner circumferential portion363 of the cancel plate 36 to press the second side wall portion 402 ofthe clutch drum 40 of the clutch C2 in the axial direction. Here, asdescribed above, the inner circumferential portion 363 of the cancelplate 36 and the second side wall portion 402 of the clutch drum 40 arefastened by the fixing portion 304 of the clutch drum 30. Therefore,when the cancel plate 36 presses the clutch drum 40, the fulcrum point(portion where the clutch drum 40 and the clutch drum 30 are fastened)and the force point (section where the clutch drum 40 supports thecancel plate 36, i.e., portion of contact between the innercircumferential portion 363 of the cancel plate 36 and the second sidewall portion 402 of the clutch drum 40) of a torsional moment that actson the clutch drum 40 correspond to substantially the same position.Thus, a large torsional moment acting on the clutch drum 40 can besuppressed, and deformation of the clutch drum 40 can be wellsuppressed.

In the clutch C1 mounted in the automatic transmission 20 according tothe embodiment described above, the first side wall portion 302 of theclutch drum 30 is formed with the plurality of oil passages 302 a, eachof which radially extends and is in communication with the firstengagement side oil chamber 34, and the plurality of second oil passages302 c, each of which radially extends and is in communication with thefirst cancel oil chamber 37. In the embodiment described above, theaxial width Da of the first oil passage 302 a and the axial width Dc ofthe second oil passage 302 c are set uniform. That is, the second oilpassage 302 c is included within the range of the axial width Da of thefirst oil passage 302 a, and the first oil passage 302 a is includedwithin the range of the axial width Dc of the second oil passage 302 c.Thus, the first oil passages 302 a for supplying oil to the firstengagement side oil chamber 34 and the second oil passages 302 c forsupplying oil to the first cancel oil chamber 37 are formed onsubstantially the same plane within the first side wall portion 302 ofthe clutch drum 30. Therefore, the first and second oil passages 302 a,302 c are not formed parallel in the axial direction, and an increase inthe axial length of the clutch C1 as well as that of the automatictransmission 20 that includes the clutch C1 and the clutch C2 can besuppressed. In addition, the first and second oil passages 302 a, 302 care both formed within the first side wall portion 302 of the clutchdrum 30. There is thus no need to use a separate member for forming theoil passages. Moreover, an increase in the number of parts can besuppressed and the clutch C1 can have a more simple and downsizedconfiguration. Consequently, according to the clutch C1 mounted in theautomatic transmission 20 of the embodiment, a hydraulic clutch with acompact and simple configuration can be achieved. However, the axialwidth Da of the first oil passage 302 a and the axial width Dc of thesecond oil passage 302 c are not necessarily set uniform. That is, if atleast one of the first and second oil passages 302 a, 302 c is includedwithin the range of the axial width of the other of the first and secondoil passage 302 a, 302 c, an increase in the axial length of the clutchC1 as well as that of the automatic transmission 20 can be suppressed.

The first oil passage 302 a and the second oil passage 302 c are eachformed in the first side wall portion 302 of the clutch drum 30 so as toalternate with each other in a radiating manner. By thus forming thefirst and second oil passages 302 a, 302 c so as to alternate with eachother in a radiating manner, the first oil passages 302 a and the secondoil passages 302 c do not overlap with each other as viewed from theaxial direction, and an increase in the axial length of the clutch C1 aswell as that of the automatic transmission 20 can be suppressed. Inaddition, oil can be equally supplied to the first engagement side oilchamber 34 and the first cancel oil chamber 37 formed into ring shapes.

Further, the first and second oil passages 302 a, 302 c are each formedfrom the hole portion that is formed penetrating radially inward fromthe outer periphery of the first side wall portion 302 of the clutchdrum 30, and the opening portion of the hole portion positioned on theouter circumferential side of the first side wall portion 302 is closedby the plug (lid element) 54. Thus, the first and second oil passages302 a, 302 c can be easily formed.

The clutch C2 serves as a second hydraulic clutch. The clutch C2includes the clutch drum 40 that serves as the second clutch drum and isdisposed circumferentially inward of the clutch drum 30; the clutch hub41 that is disposed circumferentially inward of the clutch drum 40; theplurality of clutch plates 42, 43 that is fitted in an alternatingmanner on an inner periphery of the clutch drum 40 and an outerperiphery of the clutch hub 41; and the clutch piston (second clutchpiston) 45 that defines together with the clutch drum 30 a secondengagement side oil chamber 44, and can move in the axial direction soas to press the clutch plates 42, 43 by hydraulic pressure supplied tothe second engagement side oil chamber 44. The ring-shaped fixingportion 304 axially extends from the first side wall portion 302 of theclutch drum 30. The aligning portion 305 is formed axially extendingfrom the inner circumferential side of the fixing portion 304. Thecancel plate 36 of the clutch C1 and the clutch drum 40 are fitted tothe aligning portion 305 of the fixing portion 304, and the second oilpassage 302 c is in communication with the first cancel oil chamber 37through the oil passage 302 d formed in the fixing portion 304 of theclutch drum 30. It is thus possible to dispose the clutch C1 and theclutch C2 so as to overlap as viewed from the radial direction with thesecond oil passage 302 c and the first cancel oil chamber 37 incommunication with each other.

In the automatic transmission 20 provided with the clutch C1 of theembodiment, the clutch drum 30 includes the inner cylinder portion 303axially extending from the inner circumferential portion of the firstside wall portion 302. The inner cylinder portion 303 is press-fit withthe cylindrical sleeve 52 that is rotatably supported by the fixedmember 600 of the automatic transmission 20 so as to enable the sleeve52 to rotate together with the inner cylinder portion 303. The first oilpassage 302 a is in communication with the supply passage 31 a formed inthe fixed member 600 through the oil hole 52 a formed in the sleeve 52and the relay oil passage 303 a formed in the inner cylinder portion303. The second oil passage 302 c is in communication with the supplypassage 31 c formed in the fixed member 600 through the oil hole 52 cformed in the sleeve 52 and the relay oil passage 303 c formed in theinner cylinder portion 303. Thus, even if the supply passages 31 a, 31 cformed in the fixed member 600 of the automatic transmission 20 have asimplified structure, the first and second oil passages 302 a, 302 c caneasily be in respective communication with the supply passages 31 a and31 c.

The automatic transmission 20 provided with the clutch C1 of theembodiment further includes the clutch C2 that is disposed inward of theclutch C1 so as to overlap with the clutch C1 as viewed from the radialdirection. The present invention is thus well suited for the hydraulicclutch that is disposed circumferentially outward. In other words,according to the present invention, an increase in the axial length ofthe automatic transmission 20 can be suppressed, while also supplyinghydraulic oil to the first engagement side oil chamber 34 and the firstcancel oil chamber 37 of the clutch C1 that is disposed outward of theclutch C2 that serves as the second hydraulic clutch.

Note that, as shown in FIG. 7, the cancel plate 36 may not be fastenedto the fixing portion 304, provided that an end surface of the innercircumferential portion 363 on the left side of the figure is supportedby the clutch drum 40 in the vicinity of the coupled portions of theclutch drum 30 and the clutch drum 40. Further note that the hydraulicclutch of the present invention is not limited to the automatictransmission 20 of the embodiment, and may obviously be applied to amanual transmission as well.

Here, the correspondence between main elements of the embodiment andmain elements of the invention as described in the Summary of theInvention will be explained. In the embodiment, the clutch C1 includingthe clutch drum 30 that includes at least the first outer cylinderportion 301 that holds the plurality of clutch plates 32, 33, and thefirst side wall portion 302 that extends radially inward from the firstouter cylinder portion 301; the clutch piston 35 that defines togetherwith the clutch drum 30 the first engagement side oil chamber 34 and canmove in the axial direction by hydraulic pressure supplied to the firstengagement side oil chamber 34 and press the clutch plates 32, 33; andthe cancel plate 36 that together with the clutch piston 35 defines thefirst cancel oil chamber 37 for canceling centrifugal hydraulic pressurecorresponds to a “hydraulic clutch”. The first oil passages 302 a formedin the first side wall portion 302 of the clutch drum 30 correspond to“first oil passages”. The second oil passages 302 c that are incommunication with the first cancel oil chamber 37 and formed in aradiating manner in the first side wall portion 302 so as not to overlapwith the first oil passages 302 a as viewed from the axial directioncorrespond to a “second oil passages”. The clutch C2 that is disposedinward of the clutch C1 so as to overlap with the clutch C1 as viewedfrom the radial direction corresponds to a “second hydraulic clutch”.The automatic transmission 20 corresponds to a “transmission device”.

Note that with regard to the correspondence between the main elements ofthe embodiment and the main elements of the invention as listed in theSummary of the Invention, the embodiment is only one specific examplefor carrying out the invention explained in the Summary of theInvention. This correspondence does not limit the elements of theinvention as described in the Summary of the Invention. In other words,any interpretation of the invention described in the Summary of theInvention shall be based on the description therein; the embodiment ismerely one specific example of the invention described in the Summary ofthe Invention.

The above embodiment was used to describe an example for carrying outthe present invention. However, the present invention is notparticularly limited to such an example, and may obviously be carriedout using various embodiments without departing from the scope of thepresent invention.

The present invention can be utilized in the manufacturing industry forhydraulic clutches and transmission devices provided with the same.

What is claimed is:
 1. A hydraulic clutch comprising: a clutch drum thatincludes at least: an outer cylinder portion that is fitted with aplurality of clutch plates and axially extends, an inner cylinderportion that axially extends at a radial inner side of the outercylinder portion, and a side wall portion that radially connects theouter cylinder portion and the inner cylinder portion; a clutch pistonthat defines together with the clutch drum an engagement side oilchamber, and moves in an axial direction so as to press the clutchplates by hydraulic pressure supplied to the engagement side oilchamber; and a cancel plate that defines together with the clutch pistona cancel oil chamber that cancels centrifugal hydraulic pressure,wherein: the side wall portion of the clutch drum is formed with a firstoil passage that radially extends and is in communication with theengagement side oil chamber, and a second oil passage that radiallyextends and is in communication with the cancel oil chamber, and one ofthe first and second oil passages is at least partially included in arange of an axial width of the other of the first and second oilpassages in the side wall portion.
 2. The hydraulic clutch according toclaim 1, wherein the first oil passage and the second oil passage areeach formed in a plurality in the side wall portion of the clutch drumso as to alternate with each other in a radiating manner.
 3. Thehydraulic clutch according to claim 1, wherein the first and second oilpassages are each formed from a hole portion that is formed penetratingradially inward from an outer periphery of the side wall portion of theclutch drum, and an opening portion of the hole portion positioned on anouter circumferential side of the side wall portion is closed by a lidelement.
 4. A transmission device provided with the hydraulic clutchaccording to claim 1, wherein: the hydraulic clutch is a first hydraulicclutch, the transmission device further includes a second hydraulicclutch that is disposed circumferentially inward of the first hydraulicclutch, and the first and second oil passages extend to radially outsiderather than to an engagement side oil chamber of the second hydraulicclutch.
 5. The transmission device according to claim 4, wherein thesecond hydraulic clutch includes a second clutch drum that is disposedcircumferentially inward of the clutch drum, a clutch hub that isdisposed circumferentially inward of the second clutch drum, a pluralityof second clutch plates that is fitted in an alternating manner to aninner periphery of the second clutch drum and an outer periphery of theclutch hub, and a second clutch piston that defines together with theclutch drum a second engagement side oil chamber, and moves in the axialdirection so as to press the second clutch plates by hydraulic pressuresupplied to the second engagement side oil chamber, wherein aring-shaped fixing portion axially extends from the side wall portion ofthe clutch drum, and an aligning portion is formed axially extendingfrom an inner circumferential side of the fixing portion, and the cancelplate of the first hydraulic clutch and the second clutch drum arefitted to the aligning portion of the fixing portion, and the second oilpassage is in communication with the cancel oil chamber through an oilpassage formed in the fixing portion of the clutch drum.
 6. Thetransmission device according to claim 4, wherein the clutch drumincludes an inner cylinder portion that axially extends from an innercircumferential portion of the side wall portion, and the inner cylinderportion is fitted with a cylindrical sleeve that is rotatably supportedby a fixed member of the transmission device such that the sleeverotates together with the inner cylinder portion, and the first oilpassage is in communication with a first supply passage formed in thefixed member through a first oil hole formed in the sleeve and a firstrelay oil passage formed in the inner cylinder portion, and the secondoil passage is in communication with a second supply passage formed inthe fixed member through a second oil hole formed in the sleeve and asecond relay oil passage formed in the inner cylinder portion.
 7. Thehydraulic clutch according to claim 1, wherein the clutch drum comprisesa ring shape portion that axially extends and is disposed between theouter cylinder portion and the inner cylinder portion in a radialdirection, and wherein the second oil passage communicates between thesecond oil passage and the cancel oil chamber via a third oil passagethat axially extends in the ring shape portion.
 8. A hydraulic clutchcomprising: a clutch drum that includes at least an outer cylinderportion that is fitted with a plurality of clutch plates, and a sidewall portion; a clutch piston that defines together with the clutch druman engagement side oil chamber, and moves in an axial direction so as topress the clutch plates by hydraulic pressure supplied to the engagementside oil chamber; and a cancel plate that defines together with theclutch piston a cancel oil chamber that cancels centrifugal hydraulicpressure, wherein the side wall portion of the clutch drum is formedwith a first oil passage that radially extends and is in communicationwith the engagement side oil chamber, and a second oil passage thatradially extends and is in communication with the cancel oil chamber,and one of the first and second oil passages is at least partiallyincluded in a range of an axial width of the other of the first andsecond oil passages, wherein the first and second oil passages are eachformed from a hole portion that is formed penetrating radially inwardfrom an outer periphery of the side wall portion of the clutch drum, andan opening portion of the hole portion positioned on an outercircumferential side of the side wall portion is closed by a lidelement.
 9. A hydraulic clutch comprising: a clutch drum that includesat least an outer cylinder portion that is fitted with a plurality ofclutch plates, and a side wall portion; a clutch piston that definestogether with the clutch drum an engagement side oil chamber, and movesin an axial direction so as to press the clutch plates by hydraulicpressure supplied to the engagement side oil chamber; and a cancel platethat defines together with the clutch piston a cancel oil chamber thatcancels centrifugal hydraulic pressure, wherein the side wall portion ofthe clutch drum is formed with a first oil passage that radially extendsand is in communication with the engagement side oil chamber, and asecond oil passage that radially extends and is in communication withthe cancel oil chamber, and one of the first and second oil passages isat least partially included in a range of an axial width of the other ofthe first and second oil passages, wherein the hydraulic clutch is afirst hydraulic clutch, wherein the transmission device further includesa second hydraulic clutch that is disposed circumferentially inward ofthe first hydraulic clutch, wherein the second hydraulic clutch includesa second clutch drum that is disposed circumferentially inward of theclutch drum, a clutch hub that is disposed circumferentially inward ofthe second clutch drum, a plurality of second clutch plates that isfitted in an alternating manner to an inner periphery of the secondclutch drum and an outer periphery of the clutch hub, and a secondclutch piston that defines together with the clutch drum a secondengagement side oil chamber, and moves in the axial direction so as topress the second clutch plates by hydraulic pressure supplied to thesecond engagement side oil chamber, wherein a ring-shaped fixing portionaxially extends from the side wall portion of the clutch drum, andwherein an aligning portion is formed axially extending from an innercircumferential side of the fixing portion, and the cancel plate of thefirst hydraulic clutch and the second clutch drum are fitted to thealigning portion of the fixing portion, and wherein the second oilpassage is in communication with the cancel oil chamber through an oilpassage formed in the fixing portion of the clutch drum.